KR20070050566A - Solar cell and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a solar cell having a structure capable of realizing high efficiency and a manufacturing method thereof. A solar cell according to an embodiment of the present invention includes a substrate, an electrode formed on the substrate, and a light absorption layer formed on the electrode. A contact area increase part is formed between the electrode and the light absorption layer.

Solar cell, contact, area, efficiency

Description

SOLAR CELL AND MANUFACTURING METHOD OF THE SAME

1 is a cross-sectional view showing a solar cell according to an embodiment of the present invention.

FIG. 2 is an atomic force microscope (AFM) photograph of one surface of a first electrode having irregularities formed in a solar cell according to Example 2 of the present invention.

3 is a cross-sectional view showing a solar cell according to another embodiment of the present invention.

The present invention relates to a solar cell and a method for manufacturing the same, and more particularly, to a solar cell having a structure capable of realizing high efficiency and a method for manufacturing the same.

A solar cell is a battery that generates electrical energy using solar energy, and has advantages of being environmentally friendly, infinite energy source, and long life. Examples of such solar cells include silicon solar cells and dye-sensitized solar cells.

Among these, the dye-sensitized solar cell generally includes a first electrode on which a porous membrane on which dye is adsorbed is formed, and a second electrode disposed to face each other at a predetermined interval from the first electrode. Such dye-sensitized solar cells have an advantage of low cost due to the simple manufacturing process compared to silicon solar cells. In addition, there is an advantage that can be used for building exterior walls, glass greenhouses and the like by using a transparent electrode as the first electrode and the second electrode.

However, since the photoelectric conversion efficiency of the dye-sensitized solar cell is low level, its commercialization is practically difficult. In order to improve the photoelectric conversion efficiency, a method of improving the reflectance of the second electrode or using light scatterers has been proposed, but such a method has a limitation in improving the photoelectric conversion efficiency of a dye-sensitized solar cell. Accordingly, new technologies for improving the photoelectric conversion efficiency of dye-sensitized solar cells are urgently required. This request for improving photoelectric conversion efficiency is the same for other types of solar cells.

The present invention has been made in view of the above, and an object of the present invention is to provide a solar cell and a method of manufacturing the same, which can improve photoelectric conversion efficiency.

In order to achieve the above object, a solar cell according to an embodiment of the present invention includes a first substrate, a first electrode formed on the first substrate, and a light absorption layer formed on the first electrode. A contact area increasing part is formed between the first electrode and the light absorption layer.

The contact area increasing portion may be formed of irregularities. In this case, the unevenness may be formed in the first substrate, and the unevenness may be formed in the first electrode by the unevenness formed in the first substrate.

An average squared value of the surface roughness of the first electrode may be 10 nm to 3000 nm, whereby an average squared value of the surface roughness of one surface of the first electrode on the first substrate may be 10 nm to 3000 nm.

The unevenness may include at least one of a stair shape, a mesh shape, a scratch shape, a ska shape, and a needle shape.

A second electrode is formed on a second substrate disposed opposite to the first substrate, and the surface roughness of the first electrode may be greater than the surface roughness of the second electrode. In this case, an average squared surface roughness of the first electrode may be greater than an average squared surface roughness of the second electrode.

On the other hand, the manufacturing method of the solar cell according to the present invention includes the steps of forming an electrode having a contact area increase, and forming a light absorption layer on the electrode.

In the forming of the electrode having the contact area increasing part, the electrode may be formed on one surface of the substrate on which the unevenness is formed.

The unevenness of the substrate may be formed by mechanical etching or chemical etching. The mechanical etching method may be selected from the group consisting of sandblasting, scratching and plasma etching, and the chemical etching may use a solution selected from the group consisting of nitric acid, hydrochloric acid, hydrofluoric acid, and a mixture thereof.

Hereinafter, a solar cell and a method for manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a solar cell according to an embodiment of the present invention.

Referring to FIG. 1, a solar cell according to the present embodiment includes a first substrate 10 on which a porous membrane 30 on which a first electrode 11 and a dye 40 are adsorbed is formed, and the first substrate ( A second substrate 20 which is disposed to face the substrate 10 at a predetermined interval and is disposed in a space between the first substrate 10 and the second substrate 20, and the electrolyte 50 disposed in the space between the first substrate 10 and the second substrate 20. It is configured to include). Herein, the porous membrane 30 to which the dye 40 is adsorbed may be referred to as a light absorbing layer as a part serving to generate electrons by incident light and move them to the first electrode 11. A separate case (not shown) may be provided outside the first substrate 10 and the second substrate 20.

In the present embodiment, the first substrate 10 serving as a support for supporting the first electrode 11 is formed to be transparent so that light can be incident thereon. Accordingly, the first substrate 10 may be made of glass or plastic. Specific examples of plastic include polyethylene terephthalate (PET), polyethylene naphthlate (PEN), polycarbonate (PC), polypropylene (PP), and polyimide. , PI), triacetyl cellulose (TAC), and the like.

The first electrode 11 formed on the first substrate 10 may be indium tin oxide (ITO), fluorine tin oxide (FTO), antimony tin oxide (ATO), or zinc. It may be made of a transparent material such as oxide (zinc oxide, ZO), tin oxide (TO), ZnO-Ga ₂ O ₃ , ZnO-Al ₂ O ₃ . The first electrode 11 may be formed of a single word or a laminated film of the transparent material.

In the present embodiment, the contact area increasing portion 16 is formed between the first electrode 11 and the porous membrane 30. In the present embodiment, the contact area increasing portion 16 is formed of irregularities formed in the first electrode 11. More specifically, irregularities are formed on one surface of the first substrate 10 on which the first electrode 11 is formed, thereby forming irregularities on the first electrode 11.

The root mean square (Rms) at one surface of the first substrate 10 having the unevenness is 10 nm to 3000 nm, and the porous film 30 is formed by the unevenness of the first substrate 10. The average surface roughness square on one surface of the first electrode 11 may also be 10 nm to 3000 nm.

Here, the average surface roughness square is 10 nm or more because it is practically difficult to form irregularities so that the average surface roughness square is less than 10 nm. When the average value of the surface roughness squares exceeds 3000 nm, the transmittance is lowered and the efficiency decrease due to the decrease in transmittance may be greater than the effect of improving the contact area. And, the transfer of electrons can occur more effectively when the average surface roughness squared is 3000 nm or less.

The unevennesses formed on the first substrate 10 and the first electrode 11 to serve as the contact area increasing portion 16 are formed by the first electrode 11 and the porous membrane 30 on which the porous membrane 30 is formed. It is sufficient if it is a shape which can increase a contact area. Therefore, the unevenness may have various shapes such as a step shape, a mesh shape, a scratch shape, a ska shape, and a needle shape.

As described above, the porous membrane 30 including the metal oxide particles 31 having the nanometer-level average particle diameter is formed on the first electrode 11 having the unevenness. The metal oxide particles 31 may include titanium oxide, zinc oxide, tin oxide, strontium oxide, indium oxide, iridium oxide, lanthanum oxide, vanadium oxide, molybdenum oxide, tungsten oxide, niobium oxide, magnesium oxide, aluminum oxide, yttrium oxide, Scandium oxide, samarium oxide, gallium oxide, strontium titanium oxide and the like. An example of the metal oxide particles 31 is TiO _{2, which} is a titanium oxide.

The porous membrane 30 preferably has an appropriate surface roughness while maintaining porosity by uniformly distributing metal oxide particles 31 having an average particle diameter of about nanometers.

In addition, a polymer (not shown), conductive fine particles (not shown), a light scatterer (not shown), or the like may be further added to the porous membrane 30 to improve the properties of the porous membrane 30.

The polymer added to the porous membrane 30 increases the porosity, dispersibility, and viscosity of the porous membrane 30, thereby improving the film forming properties and adhesive properties of the porous membrane 30. Suitable polymers include polyethylene glycol (PEG), polyethylene oxide (PEO), poly vinyl alcohol (PVA), poly vinyl pyrrolidone (PVP), and the like. have. Such a polymer may be selected to an appropriate molecular weight in consideration of the formation method and formation conditions of the porous membrane 30.

The conductive fine particles added to the porous membrane 30 can improve the mobility of the excitation electrons. An example of such conductive fine particles is indium tin oxide.

The light scatterer added to the porous membrane 30 serves to extend the path of light moving in the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell. The light scatterer may be made of the same material as the metal oxide particles 31 constituting the porous membrane 30, and in consideration of the light scattering effect, the light scatterer may have an average particle diameter of 100 nm or more.

And the dye 40 which absorbs external light and excites an electron is adsorb | sucked on the surface of the metal oxide particle 31 which comprises the porous film 30. The dye 40 may be, for example, a metal complex containing aluminum (Al), platinum (Pt), palladium (Pd), europium (Eu), lead (Pb), iridium (Ir), or the like, and ruthenium (Ru) composite. Can be done. Here, ruthenium is an element belonging to the platinum group, and a dye containing ruthenium is generally used as many organometallic composite compounds.

In addition, dyes, dyes that are easy to emit electrons, and organic dyes may be applied to improve the long-wave absorption of visible light to improve photoelectric conversion efficiency. The organic dye may be used alone or in combination with ruthenium complex, such organic dyes, such as coumarin, porphyrin, xanthene, riboflavin, triphenylmethan, etc. There is this.

On the other hand, the second substrate 20 disposed opposite to the first substrate 10 serves as a support for supporting the second electrode 21, it may be formed transparent. The second substrate 20 may be made of glass or plastic. Specific examples of the plastic may include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polypropylene, polyimide, and triacetyl cellulose.

The second electrode 21 formed on the second substrate 20 may be formed to face the first electrode 11 and may include a transparent electrode 21a and a catalyst electrode 21b.

The transparent electrode 21a may be made of a transparent material such as indium tin oxide, fluorine tin oxide, antimony tin oxide, zinc oxide, tin oxide, ZnO-Ga ₂ O ₃ , ZnO-Al ₂ O _3, or the like. The transparent electrode 21a may be formed of a single word or a laminated film of the transparent material. The catalyst electrode 21b serves to activate the redox couple, and includes platinum, ruthenium and palladium. It may be made of iridium, rhodium (Rh), osmium (Os), carbon (C), WO ₃ , TiO ₂ , and the like.

In this embodiment, since the unevenness | corrugation which functions as a contact area increase part is not formed in the 2nd electrode 21, the surface roughness value of the 1st electrode 11 is formed larger than the surface roughness value of the 2nd electrode 21. As shown in FIG. Here, the square root mean square value of the surface roughness of the second electrode 21 is greater than the square root mean square value of the first electrode 11. That is, the root mean square value of the surface roughness of the second electrode 21 has a value of less than 10 nm.

 The first substrate 10 and the second substrate 20 are bonded by an adhesive 61, and the electrolyte 50 is formed through the holes 25a formed in the second substrate 20 and the second electrode 21. The electrolyte 50 is impregnated between the first electrode 11 and the second electrode 21 by being injected. The electrolyte 50 is uniformly dispersed into the porous membrane 30. The electrolyte 50 serves as an iodide / triiodide pair to receive electrons from the second electrode 21 by oxidation and reduction and transfer them to the dye 40. The holes 25a formed in the second substrate 20 and the second electrode 21 are sealed by the adhesive 62 and the cover glass 63.

In the present embodiment, the electrolyte 50 is described as a liquid, but the present invention is not limited thereto, and various types of electrolytes may be disposed between the first electrode 11 and the second electrode 21.

In such a solar cell, when external light such as solar light enters into the solar cell, photons are absorbed by the dye, and the dye is transferred from the ground state to the excited state to generate electron-hole pairs. The electrons in the excited state are injected into the conduction band of the metal oxide particles 31 constituting the porous membrane 30, flow through the first electrode 11 to an external circuit (not shown), and then to the second electrode 21. Move. On the other hand, as the iodide in the electrolyte 50 is oxidized to triiodide, the oxidized dye is reduced, and the triiodide is reduced to iodide by a reduction reaction with electrons reaching the second electrode 21. The movement of electrons causes the solar cell to operate.

Unlike other solar cells, for example silicon solar cells, solar cells operate through interfacial reactions, so improvement of interfacial properties is very important. In the present embodiment, the contact area increasing portion 16 formed of irregularities is formed on the first substrate 10 and the first electrode 11 to improve the contact characteristics of the first substrate 10 and the first electrode 11. In addition, the contact area between the first electrode 11 and the porous film 30 may be improved, and the contact area may be increased to improve electron mobility and speed.

In this embodiment, the unevenness is formed by the contact area increasing portion 16. At this time, the unevenness formed in the first substrate 10 also forms the contact area increasing portion 16 formed of the unevenness in the first electrode 11 as well. By forming the irregularities on the first substrate 10, the process is easy and has an advantage in terms of the protection of the first electrode 11 than the formation of the irregularities directly on the first electrode 11. This is because when the unevenness is directly formed on the first electrode 11 by etching or the like, unwanted damage or the like may occur on the first electrode 11.

The manufacturing method of the solar cell demonstrated above is as follows.

First, a transparent first substrate 10 made of glass or plastic is prepared. Here, specific examples of the plastic include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polypropylene, polyimide and triacetyl cellulose.

Subsequently, irregularities of a shape including a step shape, a mesh shape, a scratch shape, a ska shape, a needle shape, and the like are formed on the first substrate 10 by a mechanical etching method or a chemical etching method. Examples of the mechanical etching method include sandblasting, scratching, plasma etching, and the like, and chemical etching includes hydrofluoric acid, nitric acid, hydrochloric acid, and a method of immersing the substrate in a mixed solution thereof. As a result, the root mean square value of the surface roughness of the first substrate 10 may have a value of 10 nm to 3000 nm.

Subsequently, the first electrode 11 is formed by forming a conductive film on one surface of the first substrate 10 on which the unevenness is formed by sputtering, chemical vapor deposition (CVD), spray pyrolysis deposition (SPD), or the like. Unevenness is also formed in the conductive film 11 by the unevenness formed in the first substrate 10, and the unevenness thus formed serves as the contact area increasing part 16. Due to the irregularities, the average value of the squared surface roughness of the first electrode 11 may be 10 nm to 3000 nm. The first electrode 11 formed as described above may be formed of a material such as indium tin oxide, fluorine tin oxide, antimony tin oxide, zinc oxide, tin oxide, ZnO-Ga ₂ O ₃ , ZnO-Al ₂ O _3, or the like. The first electrode 11 may be formed of a single word or a laminated film of the transparent material.

Subsequently, a paste including the metal oxide particles 31 is coated on the first electrode 11 and then heat-treated to form the porous membrane 30. The paste may further include a polymer, a light scatterer, and conductive fine particles in addition to the metal oxide.

As a method of coating the paste, various methods such as a doctor blade method, a screen printing method, a spin coating method, a spray method, and a wet coating method may be applied. Here, it is preferable to select an appropriate paste according to the coating method.

And, the heat treatment of the paste may be performed for 30 minutes at 450 to 600 ℃ when the binder is added, it may be carried out at a temperature of 200 ℃ or less when the binder is not added. However, this may vary depending on the composition of the paste, but the present invention is not limited thereto.

Subsequently, the first substrate 10 on which the first electrode 11 and the porous membrane 30 are formed is immersed in the alcohol solution in which the dye is dissolved for a predetermined time, thereby adsorbing the dye 40 to the porous membrane 30. .

Then, the transparent electrode 21a and the catalyst electrode 21b are sequentially formed on the second substrate 20 made of glass or plastic to form the second electrode 21. Since the constituent material of the second substrate 20 corresponds to the first substrate 10, description thereof will be omitted. Similarly, since the constituent material of the transparent electrode 21a corresponds to the first electrode 11, description thereof will be omitted.

The catalyst electrode 21b may be made of platinum, ruthenium, rhodium, palladium, iridium, osmium, WO ₃ , TiO ₂ , C, or the like. The catalyst electrode 21b may be formed by physical vapor deposition (electrolytic plating, sputtering, electron beam deposition, etc.) or wet coating (eg, spin coating, dip coating, flow coating, etc.). For example, when the catalyst electrode 21b is made of platinum, wet coating a solution in which H ₂ PtCl ₆ is dissolved in an organic solvent such as methanol, ethanol, or isopropyl alcohol (IPA) on the transparent electrode 21a After that, a method of heat treatment at a temperature of 400 ° C. in an air or oxygen atmosphere may be applied.

Subsequently, the first substrate 10 and the second substrate 20 are disposed such that the first electrode 11, the porous membrane 30, and the second electrode 21 face each other, and then use an adhesive 61. The first substrate 10 and the second substrate 20 are bonded to each other. As the adhesive 61, a thermoplastic polymer film (for example, trade name surlyn), an epoxy resin, and an ultraviolet curing agent can be used. In the case of using the thermoplastic polymer film as the adhesive 61, the thermoplastic polymer film is positioned between the first substrate 10 and the second substrate 20, and then heated and pressed to form the first substrate 10 and the second substrate ( 20) is bonded.

After the electrolyte 50 is injected through the holes 25a formed in the second substrate 20 and the second electrode 21, the holes 25a are sealed using the adhesive 62 and the cover glass 63. do. As a result, the manufacturing of the solar cell is completed, and a separate case (not shown) may be provided outside the first substrate 10 and the second substrate 20.

Hereinafter, the solar cell according to the present embodiment will be described in more detail with reference to Examples. These examples are only intended to illustrate the invention, but the invention is not limited thereto.

Example 1

After ultrasonic cleaning with distilled water on a first substrate made of soda-lime glass having a width of 2.2 cm, a length of 2.2 cm, and a thickness of 1.1 mm, the first substrate was immersed in an aqueous hydrofluoric acid solution containing 49 wt% hydrofluoric acid for 20 minutes. Was etched. Subsequently, after ultrasonic cleaning using distilled water on the first substrate, indium tin oxide was deposited to a thickness of 500 nm by spray pyrolysis deposition to form a first electrode.

The porous membrane of about 15㎛ containing TiO ₂ with a paste containing TiO ₂ particles of 7nm to 50nm particle size on one side of the first electrode using a screen printing method is applied to an area of 1cm ^2, and heat treated at 450 ℃ 30 bungan It was formed to a thickness.

The first substrate on which the porous membrane and the first electrode were formed was immersed in 0.3 mM ruthenium (4,4-dicarboxy-2,2'-bipyridine) ₂ (NCS) ₂ solution for 24 hours to dye the porous membrane. Adsorbed. The dye-adsorbed porous membrane was washed with ethanol.

Ultrasonic cleaning was performed on the second substrate made of soda-lime glass having a width of 2.2 cm, a length of 2.2 cm, and a thickness of 1.1 mm using distilled water. Subsequently, two holes penetrating the second substrate were formed. Subsequently, indium tin oxide was deposited to a thickness of 500 nm by the Pray pyrolysis deposition method to form a transparent electrode, and a sputtering method was used to prepare a catalyst electrode made of platinum and having a surface resistance of 3Ω / □.

The first substrate and the second substrate were disposed so that the porous membrane formed on the first electrode faced the second electrode, and then the thermoplastic polymer film was placed therebetween to heat and compress to bond the first substrate to the second substrate. The solar cell was manufactured by injecting an electrolyte through two holes formed in the second substrate and the second electrode and blocking the hole using a thermoplastic polymer film and a cover glass. At this time, the electrolyte was prepared in 100 ml of a mixed solution composed of 80% by volume of ethylene carbonate (ethylene carbornate) and 20% by volume of acetonitrile and 21.928g of tetrapropylammonium iodide and 1.931g of iodine. It is a solution in which (I ₂ ) is dissolved.

Example 2

A solar cell was manufactured in the same manner as in Example 1, except that the first substrate was etched for 40 minutes.

Example 3

A solar cell was manufactured in the same manner as in Example 1, except that the first substrate was etched for 90 minutes.

Example 4

A solar cell was manufactured in the same manner as in Example 1, except that the first substrate was etched for 150 minutes.

Example 5

A solar cell was manufactured in the same manner as in Example 1, except that the first substrate was etched for 300 minutes.

Example 6

A solar cell was manufactured in the same manner as in Example 1, except that the first substrate was etched for 600 minutes.

Comparative Example 1

A solar cell was manufactured in the same manner as in Example 1, except that the first substrate was not etched.

Comparative Example 2

A solar cell was manufactured in the same manner as in Example 1, except that the first substrate was etched for 1200 minutes.

In the solar cell of Example 2, an atomic force microscope (AFM) photograph of the surface of the first electrode on which the unevenness was formed is shown in FIG. 2. Referring to FIG. 2, it can be seen that the first electrode is formed on the first substrate on which the unevenness is formed by etching, and the unevenness is also formed on the first electrode. It can be predicted that such unevenness may increase the contact area between the first electrode and the porous membrane. In the drawings, only the first electrode surface photograph of the solar cell of Example 2 is shown, which is the same in other embodiments.

In Tables 1 to 6 and the solar cell of Comparative Examples 1 and 2, the root mean square value, open voltage, short circuit current, charge density, transmittance and efficiency of the first electrode are shown in Table 1. Here, the open circuit voltage and the like were evaluated from the voltage-current curve measured after calibrating a 100 mW / cm ² light source with a Si standard cell. Table 1 is listed in order of increasing average of the surface roughness squares for clearer understanding.

Surface roughness squared average pack [mm] Open circuit voltage [V] Short circuit current [mA] Density Transmittance [%] efficiency [%] Comparative Example 1 8 0.763 6.810 0.613 82.2 3.187 Example 1 38 0.751 7.090 0.611 82.1 3.253 Example 2 70 0.713 8.185 0.600 81.4 3.499 Example 3 180 0.724 8.214 0.595 81.3 3.538 Example 4 325 0.691 8.199 0.641 80.5 3.632 Example 5 680 0.678 8.105 0.613 80.1 3.370 Example 6 1280 0.671 8.091 0.591 79.1 3.209 Comparative Example 2 3200 0.614 7.610 0.577 76.5 2.700

It can be seen that the solar cells according to Examples 1 to 6 have very high currents and similar charge values compared to the solar cells according to Comparative Examples 1 and 2. That is, the solar cells according to Examples 1 to 6 have improved short-circuit current values than the solar cells according to Comparative Examples 1 and 2, which is expected to be due to an increase in the contact area between the porous membrane and the first electrode. That is, it can be seen that the solar cells according to Examples 1 to 6 have much better efficiency than the solar cells according to Comparative Examples 1 and 2 by excellent short-circuit current.

In this case, the transmittance decreases as the average squared surface roughness increases. In Comparative Example 2, the decrease in efficiency due to the decrease in the transmittance is greater than the increase in efficiency due to the improved short circuit current as the contact area increases. Can be.

Hereinafter, a solar cell according to another embodiment of the present invention will be described in detail with reference to FIG. 3. 3 is a cross-sectional view showing a solar cell according to another embodiment of the present invention.

This embodiment will be described in detail only with respect to the parts different from the above-described embodiment, and the same or extremely similar components use the same reference numerals. In addition, the manufacturing method of this embodiment is demonstrated in detail only about the manufacturing process of a 1st electrode, and since the other part is substantially the same as in the manufacturing method of embodiment mentioned above, detailed description is abbreviate | omitted.

In this embodiment, the 1st board | substrate 110 is a smooth board | substrate with which unevenness | corrugation is not formed, and the contact area increase part 116, for example, unevenness | corrugation is formed in the 1st electrode 111. FIG. The first electrode 111 may be formed by a sputtering method, a chemical vapor deposition method, a spray pyrolysis deposition method, or the like. At this time, the process conditions are controlled so that the first electrode 111 has a mean value of squared surface roughness of 10 nm to 3000 nm. can do.

Although the above embodiments have described that the unevenness is formed as an example of the contact area increasing portion, the present invention is not limited thereto. Therefore, various configurations that can increase the contact area between the first electrode and the porous membrane can be applied, which is also within the scope of the present invention.

In addition, although the dye-sensitized solar cell is illustrated and described as an example of the solar cell, the present invention is not limited thereto, and may be applied to other types of solar cells, which also belong to the scope of the present invention.

That is, while the embodiments and examples of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. In addition, it is natural that it belongs to the scope of the present invention.

As described above, the solar cell according to the present invention may form a contact area increase part in the first electrode on which the light absorbing layer is formed, thereby improving contact characteristics between the light absorbing layer and the first electrode and increasing the contact area. As a result, the mobility and the moving speed of the electrons in the excited state can be improved to increase the current density, and consequently, the photoelectric conversion efficiency of the solar cell can be improved.

Claims (14)

Board; An electrode formed on the substrate; And A light absorption layer formed on the electrode; Including, And a contact area increasing portion is formed between the electrode and the light absorption layer. The method of claim 1, The solar cell which the said contact area increase part consists of an unevenness | corrugation. The method of claim 2, Irregularities are formed on the substrate, A solar cell in which irregularities are formed in the electrode by the irregularities formed in the substrate. The method of claim 2, The unevenness is a solar cell having a shape including at least one of step shape, mesh shape, scratch shape, ska shape and needle shape. The method according to any one of claims 1 to 4, A solar cell having a mean square surface roughness of the electrode of 10nm to 3000nm. The method according to any one of claims 1 to 4, A solar cell having a mean square surface roughness of 10 nm to 3000 nm on one surface of the substrate on the substrate. A first substrate and a second substrate disposed to face each other; A first electrode formed on the first substrate; A light absorption layer formed on the first electrode; And A second electrode formed on the second substrate Including, The solar cell of which the surface roughness of the first electrode is larger than the surface roughness of the second electrode. The method of claim 7, wherein The solar cell square average value of the surface roughness of the first electrode is larger than the square average surface roughness of the second electrode. The method of claim 8, The solar cell of claim 1, wherein the root mean square of the surface roughness is 10 nm to 3000 nm. The method of claim 8, The solar cell of claim 1, wherein the square root of the surface roughness of one surface on which the first electrode is formed is 10 nm to 3000 nm. Forming an electrode having a contact area increasing portion; And Forming a light absorption layer on the electrode Method for manufacturing a solar cell comprising a. The method of claim 11, In the step of forming an electrode having the contact area increasing portion, the manufacturing method of a solar cell to form the electrode on a substrate on which irregularities are formed. The method of claim 12, The unevenness of the substrate is a method of manufacturing a solar cell is formed by mechanical etching or chemical etching. The method of claim 13, The mechanical etching method is selected from the group consisting of sandblasting method, scratch method and plasma etching method, the chemical etching method of manufacturing a solar cell using a solution selected from the group consisting of nitric acid, hydrochloric acid, hydrofluoric acid and a mixture thereof. .

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